Some reactions of meso-formyloctaethylporhyrin

Abstract

Grignard reactions on nickel meso-formyloctaethylporphyrin (1a) yield methyl and phenyl carbinols. The former is readily dehydrated to the meso-vinyl derivative, which by hydrogenation yields the meso-ethyl analogue, and by bromination and dehydrobromination affords the meso-ethynyl compound. The latter is readily oxidised to the 1,4-diporphyrinylbuta-1,3-diyne. Reaction of sulphuric acid with the meso-phenyl carbinol gives a meso-benzyl derivative in which one β-ethyl group has been dehydrogenated to give a β-vinyl substituent. Attempts to form a carbene from (1a) with triethyl phosphite gave the meso-propenyl compound and with boron trifluoride and zinc amalgam gave the meso-formyloxy derivative, which is transformed readily into the meso-methoxy compound. Mechanisms for these novel reactions are suggested.